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May 18, 2012

Ancient Giant Turtle Could Give Gators A Run For Their Money

by editor

Brett Smith for Redorbit.com

Florida paleontologists digging in a northern Colombia coal mine have discovered the remains of a giant turtle so big it was capable of snacking on ancient alligators, according to a new report in the online version of the Journal of Systematic Palaeontology.

The 60-million-year-old reptile, dubbed Carbonemys cofrinii or “coal turtle,” is considered to be part of a family of freshwater turtles called pelomedusidae. These turtles are also referred to a side-necked turtles because they are unable to fully withdraw their heads into their shells. Instead they draw it to the side and fold it beneath the upper edge of their shell when threatened. Modern day side-necked turtles grow to be around a foot in length and typically inhabit the mud at the bottom of rivers or shallow lakes, where they eat invertebrates such as insects, mollusks, and worms.

While working on the Columbia dig back in 2005, the Florida University team found two distinct remains of the Smart car-sized turtle, a skull and a shell. The skull measures about 9.5 inches, about the same size as an NFL football. The shell, which was found nearby and was said to belong to the same species, measures about 5 feet 7 inches long, slightly shorter than the average human male.

"This discovery is showing us that after the extinction of the dinosaurs, the tropics were a place where animals can actually succeed and get really big," said the study´s lead author Edwin Cadena, who was a master´s student at the university in 2005. "They had a lot of space and a lot of food sources so they didn't have to worry about competition with other big animals. We're seeing that the tropics 60 million years ago had so much diversity and it keeps that diversity for a long, long time."

Researchers said the turtle, which was discovered in the same cave as the remains of the largest known snake, was likely an apex predator that patrolled a large area in search of food.

"It's like having one big snapping turtle living in the middle of a lake," said paleontologist Dan Ksepka, co-author of the paper and a NC State paleontologist. "That turtle survives because it has eaten all of the major competitors for resources. We found many bite-marked shells at this site that show crocodilians preyed on side-necked turtles. None would have bothered an adult Carbonemys, though — in fact smaller crocs would have been easy prey for this behemoth."

A phylogenetic evaluation showed the coal turtle is most closely related to living species in Venezuela and Madagascar. This revelation supports a theory that says the South American and African continents were once connected in northern South America, rather than southern South America through Antarctica.

There is a large base of evidence to support to theory that Madagascar and South America were once connected. Fossil evidence from dinosaurs and other prehistoric animals points to many species inhabiting both of these now distant places. Scientists also point to a shared evolutionary background among many species living in these modern day tropical locations.